1. Field of the Invention
The present invention relates to an autonomous vehicle that can run and turn in an arbitrary direction by driving a pair of drive wheels individually. Particularly, the present invention relates to an autonomous vehicle such as an autonomous cleaning robot or an autonomous waxing robot that is used in an environment where the state of the floor affects the run.
2. Description of the Related Art
This application is based on Japanese Patent Application No. 9-045362 filed in Japan, the contents of which are hereby incorporated by reference.
Conventional autonomous vehicles include autonomous cleaning robots and autonomous waxing robots having a cleaning task unit for cleaning the floor and a waxing task unit for applying wax on the floor attached to the rear of the chassis that carries out the autonomous travel. Such apparatuses have a pair of drive wheels at the bottom of the chassis and a driven wheel for supporting the chassis. The apparatus can run in an arbitrary direction or turn at a certain site by providing individual control of each of the drive wheels. The apparatus autonomously selects a course according to the environmental situation to run according to a program prepared in advance. The floor is cleaned or waxed in this manner. The autonomous travel is controlled according to the distance of travel of each of the drive wheels forming a pair.
There is a possibility of the drive wheels of the autonomous vehicle slipping on the floor due to external force and depending on the state of the floor. The floor is particularly slippery when the floor is cleaned or when a coat of wax is applied, so that the possibility of slipping becomes higher. In a conventional autonomous vehicle, the control of the autonomous travel is implemented according to the distance of travel of the drive wheels. Therefore, the actual orientation of the chassis can differ from the angle envisaged in controlling the autonomous travel by the occurrence of slipping. On this occasion, there was a problem that autonomous travel could not be carried out properly. This problem is particularly serious at the time of a specific travel inducing the occurrence of slipping such as at the rotation of the chassis.